v7 man page for wall

WALL(1M)																  WALL(1M)

NAME
       wall  -	write to all users

SYNOPSIS
       /etc/wall

DESCRIPTION
       Wall  reads  its  standard  input  until an end-of-file.  It then sends this message, preceded by `Broadcast Message ...', to all logged in
       users.

       The sender should be super-user to override any protections the users may have invoked.

FILES
       /dev/tty?
       /etc/utmp

SEE ALSO
       mesg(1), write(1)

DIAGNOSTICS
       `Cannot send to ...' when the open on a user's tty file fails.

																	  WALL(1M)